To detect cells, a 5th Generation (5G) user equipment (UE) must perform a cell search procedure similar to legacy Radio Access Technologies (RATs). The cell search is used to obtain synchronization to the 5G Transmission Point (TP), e.g. base station, and acquire system parameters such as cell ID. In order to provide optimal performance and to minimize coverage outage, the cell search mechanism has to reliably detect cells in low signal-to-interference-plus-noise ratio (SINR) conditions to facilitate beam re-selection and inter-RAT handover at the cell edge.
UEs in Long Term Evolution (LTE) networks utilized reference signals such as Primary Synchronization Signals (PSSs) and Secondary Synchronization Signals (SSSs) to establish and maintain time synchronization with LTE cells. In LTE, timing synchronization is achieved through a two-stage detection process. Initial half-frame (i.e. 5 ms) timing is acquired through the time correction of the PSS. The SSS then resolves the timing ambiguity to a radio-frame boundary and acquires the cellID.
5G will introduce a third synchronization signal: the Extended Synchronization Signal (ESS) in order to solve the timing ambiguity of the PSS and SSS signals being repeated multiple times, typically fourteen times, in 5G within a measurement subframe. The ESS will be frequency rotated, i.e. cyclic shifted, in the frequency domain in order to resolve the transmitted symbol index. Accordingly, an efficient and accurate method, as well as corresponding device, is needed to detect the cyclic shift in the 5G cell search procedure.